1Combine all ingredients for the tart shell. Wrap in plastic or place in a air tight baggie. Refrigerate and rest of at least 2 hours.
On floured parchment, roll out the dough and line within a tart pan. Trim the edges and then place in the freezer for about 30 minutes.
Preheat the oven to 350 degrees F. Blind bake the tart shell for about 10 minutes.
In the meantime, mix apples, 1/4 cup brown sugar, cinnamon and 2 tablespoons maple syrup. Sprinkle the crust with 1 tablespoon of brown sugar and place the apples over it. Bake in the oven for about 30 minutes.
In a bowl, beat sour cream, egg yolks, 1 tablespoon maple syrup and vanilla. Pour the mixture over the apples and bake for an additional 15 minutes or until the filling has set.